Add tests for reducers and components

[namsnath]

Most components and reducers do not have tests as of now.
Tests are implemented for timetable and course reducers, but lack certain cases/tests.

Specific tests that need to be implemented:

• Timetable reducer/slice
  • updateClashmap() utility function
  • syncTimetable Thunk call with redux-mock-store. rejected/pending/fulfilled reducer tests implemented.
• Empty String Checks/Tests
  • Filter Controls -> setSelectedCategory
  • curriculumReducer/setSelectedCurriculum
  • themeReducer/changeTheme
  • timetableReducer/changeTimetable
• Dashboard Component
  • Dispatches
  • Thunk calls with redux-mock-store
  • Snapshot Testing
  • Alerts